Starter for engines



R. QDI-:LL

STARTER Foa ENGINES June 4, 1940.

Filed May 19, 193g ft j 2@ 6J 4 Patented June 4, 1940 UNITED STATES PATENT OFFICE".

3 Claims.

My invention relates more particularly to a starter for internal combustion engines, and one object of the invention is to provide a simple, reliable an-d efficient automatic device of this character. Another object is to provide a starter adapted for use with various starting motors independently of their normal direction of rotan tion. Another object Ais to provide a starting mechanism which includes a friction driving element adapted to slip under excessive load so as to avoid undue strain upon the driving and driven parts. And a further object is to provide an engine starter in which the cam means which shifts the ydriving pinion into driving position is designed with ample Contact faces arranged in balanced relation with respect to the axis of the driving member, and of sufficient pitch to insure prompt engagement of the pinion with a gear to be driven by it.

In the drawing: v

Fig. 1 is a substantially axial sectional view showing the driving motor shaft and parts associated therewith embodying this invention.

Fig. 2 is a side elevation ofthe structure shown in Fig. 1, but illustrating the driving pinion partially shifted into working position with the shifting cam in a corresponding relation.

Fig. 3 is a face view of the friction clutch member.

30 Fig. 4 is an end view of the clutch member with which the driving pinion is associated.

Figs. 5 and 6 are perspective views of the cooperating cam members showing their working faces.

Usually, and preferably, the starting device for an internal combustion engine, particularly of the type employed for driving automobiles and motor trucks, includes an electric motor, and the driving member is a pinion operatively connected to the motor shaft and temporarily engaged with gear teeth formed on or adjacent the fly wheel of the engine for rotating the latter until the explosive action in the engine cylinders has commenced; and when this takes place the pinion is automatically withdrawn from mesh with the-gear teeth of the engine y wheel, and the electric motor is allowed to come to rest until again required for starting service. My invention relates to apparatus of this type. The electric driving motor itself is not shown in the drawing, but I have indicated at l a portion of a cast frame which may be secured by suitable bolts or screws extending through holes 4, 4 into engagement with the frame or housing of the electric starting motor, and mounted in accurate 'indicated at B in dotted outline.

relationship to the y wheel or other engine part with which the starter is to cooperate. A portion of a drive shaft, which may be understood as the motor armature shaft, is'shown at 2, with an extension 2a of reduced diameter which car-- ries the hub 32L of a face cam 3 keyed rigidly to the shaft. A cooperating face cam 6 is loosely carried on the shaft adjacent the cam 3 and in position to engage the friction facing 1 of a clutch member 8, which is formed asy an integral ange of the driving pinion A also loosely mounted on the shaft extension 2a. The normal or initial position of the gear teeth of the driven member, such as the fly wheel of the engine, is A spring 9 coiled about the shaft 2a reacts between the pinion A and a two-part sleeve Iii, llia fixed to the shaft 2a in spaced relation to the pinion.

The opposing and cooperating faces 3X and 6X of the cam members, 3 and 6, respectively, are inclined to the axis of rotation, so that the sudden rotational movement of the armature shaft 2, which occurs when the starting motor is energized, causes the cam face 3x to slip over the cam surface 6X and thus to shift the cam 6 longitudinally along the shaft portion 2e, forcing with it the clutch flange and the pinion A. This movement compresses` the spring 9 and continues until the hub or end face of the pinion A engages the end of the fixed sleeve l0 as a stop, in which position the teeth of the gear A are fully meshed with the teeth B on the driven. member, such as the engine y wheel. Continuing rotation of the starting motor will thus initiate rotation of the engine fly wheel, but as soon as the engine picks up speed, the starting current will be cut off from the motor which drives the shaft 2a, and the expansive force of the spring 9, reactingagainst sleeve lila will shift the pinion A back to its initial position, incidentally rotating the cam member E through a sufficient angle for snugly fitting one cam face into the other in the relation indicated in Fig. l.

The cam face 3X is formed with two high points disposed at diarnetrically opposite sides of the axis, and with two low points each circumferentially half-way between the two high points of the cam; the cooperating face (ix of the cam S is correspondingly shaped to fit snugly against the entire surface of the cam` face 3X when the pinion A is shifted to its inactive position, as shown in Fig, 1. This means that something less than a quarter turn of the cam 3, with respect to cam 6, will serve to shift the pinion A through its full range into driving position; and, similarly,

a reverse quarter turn of one cam with respect to the other will permit the spring 9 to shift the pinion A back to inactive position. 'I'he symmetrical formation of the cam faces with two diametrically opposite high points renders them operative in either direction, so that it will make no difference whether the starting motor (not shown) which drives the shaft 2a, is arranged to rotate clockwise or counterclockwise, and the cam and gear assembly will be equally well adapted to either situation.

Furthermore, the cam faces are so designed as to have a maximum area in actual Contact at any of their relative positions, so that the bearing pressure between the cam faces shall be well distributed, resulting in substantially even wear, if any, and maintaining the original contour as closely as possible. And since each cam is, in effect, a double cam, operating simultaneously at opposite sides of the axis of rotation, the thrust transmitted from the cam 3 against the cam 6, is applied in a balanced manner so as to result directly in longitudinal movement of the cam 6 along the axis of the shaft Without introducing any bending or whipping strains upon the shaft itself.

The friction facing 1, which is secured to the face of the flange 8 by countersunk screws I5, may be of any suitable material, such as woven cotton belting, brake lining composition or other material commonly employed for clutch facings. Cooperating with the flat transaxial face GY of the member 6, this friction facing permits slippage between the cam member 6 and the gear A, as the teeth of the latter mesh with the teeth of the gear B and assume the load of driving the engine. Thus the starting motor operating the shaft 2a may continue to rotate rapidly, and will rotate the cam member 6 at the same speed, but only a portion of this speed will be transmitted through the friction facing 1 until the static inertia of the engine has been overcome. The pitch of the cam surfaces 3X and 6x is such that a full quarter turn would shift the part 6 farther than the spacing between the pinion A and the stop sleeve I0 will permit; hence, the pinion collides with the stop I0 before the high points of the cam 3 have reached the high points of the cam 6. In other words, the cams will never shift through as much as a full quarter turn, and when their relative rotation is suddenly checked by engagement of the pinion B with the stop sleeve IQ, the slippage of the friction lining 'l against the surface GY will prevent shock or damage to the parts, in addition to easing the pick-up of the driven gear B.

As shown in the drawing, the driving cam 3 is rotatively engaged with the shaft extension 2a by means of a Woodruff key l I, and may be fixed against longitudinal movement on the shaft by means of a set screw l2 impinging upon a flattened area i3 formed on the shaft. The stop sleeves 1B and IE!a are shown secured by means of pins M extending through the shaft 2a. These and other details may, of course, be varied in accordance withthe judgment of the manufacturer without departing from the spirit and scope of the invention as dened in the appended claims.

I claim:

1. In an engine starter, the combination of a driving shaft, a driving cam fixed thereon, a driven cam loosely carried on the shaft and a pinion loose on the shaft adjacent said driven cam with means providing a drive connection between said last mentioned cam and the pinion, said driving cam having diametrically opposite high portions and intermediate low portions each disposed half-way between the high portions with oppositely inclined surfaces extending from each high portion to the low portions respectively, and the driven cam being of inter-fitting contour whereby rotation of the driving cam in either direction with respect to the driven cam operates to shift the driven cam and the pinion along the shaft, and stop means on the shaft limiting such shifting movement at a point at which the relative rotation of the cams is checked at an angle less than that required for registration of their high portions.

2. In an engine starter, the combination of a driving shaft, a driving cam fixed thereon, a driven cam loosely carried on the shaft and a pinion loose on the shaft adjacent said driven cam with fiat transaxially disposed frictionally engaged surfaces providing the only drive connection between said last mentioned cam and the pinion, said driving cam having diametrically opposite high portions and intermediate low portions, and the driven cam being of inter-fitting contour whereby the relative rotation of said cams shifts the driven cam and the pinion longitudinally on the shaft with diametrically opposite portions of the cam faces in operative engagement throughout the shifting movement, and l positive stop means limiting said movement to an angle less than that required for registration of the high portions of one cam with the high portions of the other.

3. In an engine starter, the combination of a driving shaft, a driving cam xed thereon, a driven cam loosely vcarried on the shaft and a pinion loose on the shaft adjacent said driven cam with flat transaxially disposed frictionally engaged surfaces providing a drive connection between said last mentioned cam and the pinion, said driving cam having diametrically opposite high portions and intermediate low portions, and the ldriven cam being of inter-fitting contour whereby the relative rotation of said cams shifts the driven cam and the pinion longitudinally on the shaft with diametrically opposite portions of the cam faces in operative engagement throughout the shifting movement, and a positive stop on the shaft limiting the movement of the driven cam and the pinion along the shaft, and limiting relative rotation of the cams to an angle less than that required for registration of their high points, together with a spring acting axially against the pinion and pressing it toward the driven cam for providing an initial driving pressure between the said frictionally engaged surfaces.

RODMAN ODELL. 

